This program focuses on efforts to complete Einstein’s quest for a grand unifying theory that will explain all of the forces of nature in the same terms. Will string theory provide the key? Mathematical physicist Nathan Seiberg explains his research on string theory in various dimensions and on particle physics; Edward Witten, named one of the 25 most influential Americans by Time magazine, defines M theory; and theoretical physicist Juan Maldacena suggests a way to unite quantum mechanics and general relativity. A contradictory view of string theory is delivered with genial skepticism by Freeman Dyson. Segments highlighting Einstein’s research are also included. (57 minutes)